Quorn is a mushroom-based meat substitute. It's available as chicken patties, chicken nuggets and as hamburger patties.

It's horrendously expensive compared to the meats it mimics, and frankly it does not mimic hamburger all that well. On the other hand, it does an excellent job of faking processed chicken breast. I'd eat it in preference to chicken breast patties or chicken nuggets regularly if the makers could just get the price down to something less than highway robbery.